This invention relates to mounting assemblies for supporting vehicle accessories in vehicles, and more particularly, to a mounting assembly for supporting a rearview mirror or other vehicle accessory from a surface such as the inside of the front windshield of a vehicle.
Conventional windshield mounted rearview mirror support assemblies typically include base member adhered to the inside windshield surface and a support member, known in the industry as a "channel mount", slidably fitted thereover. The support member or channel mount usually includes an arm, ball joint or other structure for suspending a rearview mirror assembly in the vehicle compartment for use by the driver of the vehicle. Alternately, the mounting assembly may support other vehicle accessories such as headlight dimming switches or other items useful by persons within the vehicle passenger compartment.
Typically, the support member in a conventional mounting assembly is secured to the base member by a set screw which is tightened during manufacture of the vehicle to hold the accessory securely to the base member on the windshield. However, use of such a set screw has created numerous manufacturing and maintenance problems in such assemblies.
For example, it is difficult to maintain consistent screw threads since the set screws are typically purchased as low priced commodity items with low tolerances. The inconsistency in such threads can result in cross-threading of the screw in its aperture which causes automatic screwdrivers used in vehicle assembly to stop prematurely at a preset stall torque eve though the support is not firmly tightened against the base member. Alternately, the screws may fit so sloppily that there is no torque. Also, the set screw is often stripped out by overtightening because of the improper sizing of the socket to the set screw or a weakness in the threads of the screw itself. Consequently, the support member fits loosely on the base member and creates a perception of poor quality in the rearview mirror or other accessory which is immediately apparent to the purchaser of the vehicle. In addition, looseness at the support for the rearview mirror creates blurred and poor imaging on the mirror surface.
In addition, prior to sliding the support over the base member, should the set screw be inserted too far into its mounting aperture, assembly is prevented until the screw is backed out, causing a loss of time and significant delays in mass production situations.
In the event the set screw is properly tightened on the support member against the base member, it typically generates a force of approximately 900 pounds at the screw tip. This causes the base member and support member to tightly conform to one another but can also cause cracking, breakage or other failure of the support allowing the rearview mirror to fall, especially when the vehicle is subjected to vibration on rough roads. In addition, since many of the supporting channel mounts are manufactured from zinc, the high force generated by the set screw can create creep between the parts of the assembly over time and a consequent relaxation in the joint because of thermal cycling. Again, this results in a loose fit, poor quality perception and imaging problems.
In the past, mounting assemblies eliminating the set screw have been tried with less than satisfactory results. For example, see U.S. Pat. Nos. 4,254,931 and 4,632,348, both of which include spring members substituted for the set screws. In such assemblies, the springs have generally been inadequate to maintain a tight fit over the life of the assembly. Up and down rocking motion or side-to-side lateral motion is still experienced resulting in vibration and blurred images.
Yet other attempts have combined springs or resilient parts with set screws as for example in U.S. Pat. No. 3,928,894. Such assemblies do not eliminate the problems inherent in the use of set screws nor have they overcome the vertical and lateral motion an vibration encountered in prior known spring biased mounting assemblies.
Accordingly, the present invention was conceived in an effort to overcome the above and other problems and to provide a more secure, stable rearview mirror and/or vehicle accessory mounting assembly without the need for a set screw.